Blogs

About this blog

I'm a well-known mainframe performance guy, with almost 30 years of experience helping customers manage systems. I also dabble in lots of other technology. I've sought to widen the Performance role, incorporating aspects of infrastructural architecture.
I'm a world-famous podcaster and screencaster (albeit VERY thinly spread). :-)

Find us on Facebook

I had to eat a little bit of humble pie today - because I made an elementary mistake. I'm going to share it with you - to save you making it, too. :-) And I'm very sure I'm not going to make it in a customer situation. (Residencies are great for making mistakes in a safe environment.) :-) In CFLEVEL 15 and z/OS Release 9 RMF you get a new field at the structure level: R744SETM. This is the CPU... [More]

I've just re-read the XCF (74-2) and CF (74-4) sections of the z/OS Release 9 SMF Manual. There are some nice things in there... XCF (74-2) Number of buffer 1KB blocks by path (R742PUSE). This should tell you whether memory waste by over-specifying CLASSLEN is a problem. And some of the other scenarios. Member job name (R742MJOB). I'd like to believe this would tell us which IRLM a given member... [More]

Following on from Coupling Facility Async / Sync Thresholds - They Are A'Changin' I've been informed by Development there is a new improved write up on how the Dynamic Sync/Async conversion works in Chapter 6 of the z/OS Release 9: Setting Up A Sysplex manual. I've read it and it is VERY good. One thing to pull out is that there isn't just one threshold... There are different thresholds for Lock... [More]

APAR OA21635 is one of a rare breed: A change to the thresholds for z/OS's automatic CF Request conversion. (I'm told this has only happened once before.) If you recall z/OS Release 2 (in 2001) introduced a very nice function that automatically converts Coupling Facility requests from Sync to Async, based on thresholds. The purpose of this is to minimise the CPU cost for a coupled z/OS system,... [More]